(1) This section shall apply to all employers engaged in the laboratory use of hazardous chemicals as defined below.

(2) Where this section applies, it shall supersede, for laboratories, the requirements of all other OSHA health standards in 29 CFR part 1910, subpart Z, except as follows:

(i) For any OSHA health standard, only the requirement to limit employee exposure to the specific permissible exposure limit shall apply for laboratories, unless that particular standard states otherwise or unless the conditions of paragraph (a)(2)(iii) of this section apply.

(ii) Prohibition of eye and skin contact where specified by any OSHA health standard shall be observed.

(iii) Where the action level (or in the absence of an action level, the permissible exposure limit) is routinely exceeded for an OSHA regulated substance with exposure monitoring and medical surveillance requirements paragraphs (d) and (g)(1)(ii) of this section shall apply.

(3) This section shall not apply to:

(i) Uses of hazardous chemicals which do not meet the definition of laboratory use, and in such cases, the employer shall comply with the relevant standard in 29 CFR part 1910, subpart Z, even if such use occurs in a laboratory.

(ii) Laboratory uses of hazardous chemicals which provide no potential for employee exposure. Examples of such conditions might include:

(A) Procedures using chemically-impregnated test media such as Dip-and-Read tests where a reagent strip is dipped into the specimen to be tested and the results are interpreted by comparing the color reaction to a color chart supplied by the manufacturer of the test strip; and

(B) Commercially prepared kits such as those used in performing pregnancy tests in which all of the reagents needed to conduct the test are contained in the kit.

(b) Definitions—’’Action level” means a concentration designated in 29 CFR part 1910 for a specific substance, calculated as an eight (8)-hour time-weighted average, which initiates certain required activities such as exposure monitoring and medical surveillance.

“Assistant Secretary” means the Assistant Secretary of Labor for Occupational Safety and Health, U.S. Department of Labor, or designee. “Carcinogen” (see “select carcinogen”).

“Chemical Hygiene Officer” means an employee who is designated by the employer, and who is qualified by training or experience, to provide technical guidance in the development and implementation of the provisions of the Chemical Hygiene Plan. This definition is not intended to place limitations on the position description or job classification that the designated individual shall hold within the employer’s organizational structure.

“Chemical Hygiene Plan” means a written program developed and implemented by the employer which sets forth procedures, equipment, personal protective equipment and work practices that (i) are capable of protecting employees from the health hazards presented by hazardous chemicals used in that particular workplace and (ii) meets the requirements of paragraph (e) of this section. “Combustible liquid” means any liquid having a flashpoint at or above 100 deg. F (37.8 deg. C), but below 200 deg. F (93.3 deg. C), except any mixture having components with flashpoints of 200 deg. F (93.3 deg. C), or higher, the total volume of which make up 99 percent or more of the total volume of the mixture.

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OCR for page 289
Appendix A: OSHA
Laboratory Standard
29 CFR 1910.1450—Occupational Exposure to (A) Procedures using chemically-im-
Hazardous Chemicals in Laboratories pregnated test media such as Dip-
and-Read tests where a reagent strip is
(a) Scope and application. dipped into the specimen to be tested
and the results are interpreted by com-
(1) This section shall apply to all employers en- paring the color reaction to a color chart
gaged in the laboratory use of hazardous chemi- supplied by the manufacturer of the test
cals as defined below. strip; and
(2) Where this section applies, it shall supersede, (B) Commercially prepared kits such
for laboratories, the requirements of all other as those used in performing pregnancy
OSHA health standards in 29 CFR part 1910, sub- tests in which all of the reagents needed
part Z, except as follows: to conduct the test are contained in the
kit.
(i) For any OSHA health standard, only the
requirement to limit employee exposure to (b) Definitions—’’Action level” means a concentra-
the specific permissible exposure limit shall tion designated in 29 CFR part 1910 for a specific sub-
apply for laboratories, unless that particular stance, calculated as an eight (8)-hour time-weighted
standard states otherwise or unless the con- average, which initiates certain required activities such
ditions of paragraph (a)(2)(iii) of this section as exposure monitoring and medical surveillance.
apply. “Assistant Secretary” means the Assistant Secretary
of Labor for Occupational Safety and Health, U.S.
(ii) P rohibition of eye and skin contact Department of Labor, or designee. “Carcinogen” (see
where specified by any OSHA health stan- “select carcinogen”).
dard shall be observed. “Chemical Hygiene Officer” means an employee
who is designated by the employer, and who is quali-
(iii) Where the action level (or in the absence fied by training or experience, to provide technical
of an action level, the permissible exposure guidance in the development and implementation of
limit) is routinely exceeded for an OSHA the provisions of the Chemical Hygiene Plan. This
regulated substance with exposure monitor- definition is not intended to place limitations on the
ing and medical surveillance requirements position description or job classification that the des-
paragraphs (d) and (g)(1)(ii) of this section ignated individual shall hold within the employer’s
shall apply. organizational structure.
“Chemical Hygiene Plan” means a written program
(3) This section shall not apply to: developed and implemented by the employer which
sets forth procedures, equipment, personal protective
(i) Uses of hazardous chemicals which do equipment and work practices that (i) are capable of
not meet the definition of laboratory use, protecting employees from the health hazards pre-
and in such cases, the employer shall comply sented by hazardous chemicals used in that particular
with the relevant standard in 29 CFR part workplace and (ii) meets the requirements of para-
1910, subpart Z, even if such use occurs in a graph (e) of this section. “Combustible liquid” means
laboratory. any liquid having a flashpoint at or above 100 deg. F
(37.8 deg. C), but below 200 deg. F (93.3 deg. C), except
(ii) Laboratory uses of hazardous chemicals any mixture having components with flashpoints of
which provide no potential for employee ex- 200 deg. F (93.3 deg. C), or higher, the total volume of
posure. Examples of such conditions might which make up 99 percent or more of the total volume
include: of the mixture.
289

OCR for page 289
290 PRUDENT PRACTICES IN THE LABORATORY
“Compressed gas” means: (i) A gas or mixture of tion, absorption of moisture, spontaneous chemi-
gases having, in a container, an absolute pressure ex- cal change, or retained heat from manufacturing
ceeding 40 psi at 70 deg. F (21.1 deg. C); or (ii) A gas or processing, or which can be ignited readily and
or mixture of gases having, in a container, an absolute when ignited burns so vigorously and persistently
pressure exceeding 104 psi at 130 deg. F (54.4 deg. C) as to create a serious hazard. A chemical shall be
regardless of the pressure at 70 deg. F (21.1 deg. C); considered to be a flammable solid if, when tested
or (iii) A liquid having a vapor pressure exceeding 40 by the method described in 16 CFR 1500.44, it
psi at 100 deg. F (37.8 deg. C) as determined by ASTM ignites and burns with a self-sustained flame at a
D-323-72. rate greater than one-tenth of an inch per second
“Designated area” means an area which may be used along its major axis.
for work with “select carcinogens,” reproductive toxins
or substances which have a high degree of acute toxic- “Flashpoint” means the minimum temperature at
ity. A designated area may be the entire laboratory, such which a liquid gives off a vapor in sufficient concentra-
as a laboratory hood. tion to ignite when tested as follows:
“Emergency” means any occurrence such as, but
not limited to, equipment failure, rupture of contain- (i) Tagliabue Closed Tester (See American Na-
ers or failure of control equipment which results in an tional Standard Method of Test for Flash Point by
uncontrolled release of a hazardous chemical into the Tag Closed Tester, Z11.24-1979 (ASTM D 56-79))-
workplace. for liquids with a viscosity of less than 45 Saybolt
“Employee” means an individual employed in a Universal Seconds (SUS) at 100 deg. F (37.8 deg.
laboratory workplace who may be exposed to hazard- C), that do not contain suspended solids and do
ous chemicals in the course of his or her assignments. not have a tendency to form a surface film under
“Explosive” means a chemical that causes a sudden, test; or
almost instantaneous release of pressure, gas, and heat
when subjected to sudden shock, pressure, or high (ii) Pensky-Martens Closed Tester (See American
temperature. National Standard Method of Test for Flashpoint
“Flammable” means a chemical that falls into one of by Pensky-Martens Closed Tester, Z11.7-1979
the following categories: (ASTM D 93-79))—for liquids with a viscosity
equal to or greater than 45 SUS at 100 deg. F (37.8
(i) “Aerosol, flammable” means an aerosol that, deg. C), or that contain suspended solids, or that
when tested by the method described in 16 CFR have a tendency to form a surface film under test;
1500.45, yields a flame protection exceeding 18 or
inches at full valve opening, or a flashback (a
flame extending back to the valve) at any degree (iii) Setaflash Closed Tester (see American Na-
of valve opening; tional Standard Method of Test for Flash Point
by Setaflash Closed Tester (ASTM D 3278-78)).
(ii) “Gas, flammable” means: (A) A gas that, at Organic peroxides, which undergo autoaccelerat-
ambient temperature and pressure, forms a flam- ing thermal decomposition, are excluded from any
mable mixture with air at a concentration of 13 of the flashpoint determination methods specified
percent by volume or less; or (B) A gas that, at above.
ambient temperature and pressure, forms a range
of flammable mixtures with air wider than 12 “Hazardous chemical” means a chemical for which
percent by volume, regardless of the lower limit. there is statistically significant evidence based on
at least one study conducted in accordance with es-
(iii) “Liquid, flammable” means any liquid hav- tablished scientific principles that acute or chronic
ing a flashpoint below 100 deg F (37.8 deg. C), health effects may occur in exposed employees. The
except any mixture having components with term “health hazard” includes chemicals which are
flashpoints of 100 deg. C) or higher, the total of carcinogens, toxic or highly toxic agents, reproductive
which makes up 99 percent or more of the total toxins, irritants, corrosives, sensitizers, hepatotoxins,
volume of the mixture. nephrotoxins, neurotoxins, agents which act on the
hematopoietic systems, and agents which damage the
(iv) “ Solid, flammable” means a solid, other lungs, skin, eyes, or mucous membranes. Appendices
than a blasting agent or explosive as defined in A and B of the Hazard Communication Standard (29
1910.109(a), that is liable to cause fire through fric- CFR 1910.1200) provide further guidance in defining

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291
WORKING WITH CHEMICALS
the scope of health hazards and determining whether sician for the purpose of determining what medical
or not a chemical is to be considered hazardous for examinations or procedures, if any, are appropriate
purposes of this standard. in cases where a significant exposure to a hazardous
chemical may have taken place.
“Laboratory” means a facility where the “laboratory
use of hazardous chemicals” occurs. It is a workplace “Organic peroxide” means an organic compound that
where relatively small quantities of hazardous chemi- contains the bivalent —O—O— structure and which
cals are used on a non-production basis. may be considered to be a structural derivative of
hydrogen peroxide where one or both of the hydrogen
“Laboratory scale” means work with substances in atoms have been replaced by an organic radical.
which the containers used for reactions, transfers, and
other handling of substances are designed to be easily “Oxidizer” means a chemical other than a blasting
and safely manipulated by one person. agent or explosive as defined in 1910.109(a), that
initiates or promotes combustion in other materials,
“Laboratory scale” excludes those workplaces whose thereby causing fire either of itself or through the re-
function is to produce commercial quantities of lease of oxygen or other gases.
materials.
“Physical hazard” means a chemical for which there
“Laboratory-type hood” means a device located in is scientifically valid evidence that it is a combustible
a laboratory, enclosure on five sides with a movable liquid, a compressed gas, explosive, flammable, an
sash or fixed partial enclosed on the remaining side; organic peroxide, an oxidizer pyrophoric, unstable
constructed and maintained to draw air from the (reactive) or water-reactive.
laboratory and to prevent or minimize the escape of air
contaminants into the laboratory; and allows chemical “Protective laboratory practices and equipment”
manipulations to be conducted in the enclosure with- means those laboratory procedures, practices and
out insertion of any portion of the employee’s body equipment accepted by laboratory health and safety
other than hands and arms. Walk-in hoods with adjust- experts as effective, or that the employer can show to
able sashes meet the above definition provided that the be effective, in minimizing the potential for employee
sashes are adjusted during use so that the airflow and exposure to hazardous chemicals.
the exhaust of air contaminants are not compromised
and employees do not work inside the enclosure dur- “Reproductive toxins” means chemicals which affect
ing the release of airborne hazardous chemicals. the reproductive chemicals which affect the reproduc-
tive capabilities including chromosomal damage (mu-
“Laboratory use of hazardous chemicals” means han- tations) and effects on fetuses (teratogenesis).
dling or use of such chemicals in which all of the fol-
lowing conditions are met: “Select carcinogen” means any substance which meets
one of the following criteria:
(i) Chemical manipulations are carried out on a
“laboratory scale;” (i) It is regulated by OSHA as a carcinogen; or
(ii) Multiple chemical procedures or chemicals (ii) It is listed under the category, “known to be
are used; carcinogens,” in the Annual Report on Carcino-
gens published by the National Toxicology Pro-
(iii) The procedures involved are not part of a gram (NTP) (latest edition); or
production process, nor in any way simulate a
production process; and (iii) It is listed under Group 1 (“carcinogenic to
humans”) by the International Agency for Re-
(iv) “Protective laboratory practices and equip- search on Cancer Monographs (IARC) (latest edi-
ment” are available and in common use to mini- tions); or
mize the potential for employee exposure to
hazardous chemicals. (iv) It is listed in either Group 2A or 2B by IARC
or under the category, “reasonably anticipated
“Medical consultation” means a consultation which to be carcinogens” by NTP, and causes statisti-
takes place between an employee and a licensed phy- cally significant tumor incidence in experimental

OCR for page 289
292 PRUDENT PRACTICES IN THE LABORATORY
animals in accordance with any of the following this section is non-mandatory but provides guidance
criteria: (A) After inhalation exposure of 6-7 hours to assist employers in the development of the Chemical
per day, 5 days per week, for a significant portion Hygiene Plan.)
of a lifetime to dosages of less than 10 mg/m(3);
(B) After repeated skin application of less than 300 (1) Where hazardous chemicals as defined by
(mg/kg of body weight) per week; or (C) After this standard are used in the workplace, the em-
oral dosages of less than 50 mg/kg of body weight ployer shall develop and carry out the provisions
per day. of a written Chemical Hygiene Plan which is:
“Unstable (reactive)” means a chemical which in the (i) Capable of protecting employees from
pure state, or as produced or transported, will vigor- health hazards associated with hazardous
ously polymerize, decompose, condense, or will be- chemicals in that laboratory and
come self-reactive under conditions of shocks, pressure
or temperature. (ii) Capable of keeping exposures below
the limits specified in paragraph (c) of this
“Water-reactive” means a chemical that reacts with wa- section.
ter to release a gas that is either flammable or presents
a health hazard. (2) The Chemical Hygiene Plan shall be readily
available to employees, employee representatives
(c) Permissible exposure limits. For laboratory uses and, upon request, to the Assistant Secretary.
of OSHA regulated substances, the employer shall
assure that laboratory employees’ exposures to such (3) The Chemical Hygiene Plan shall include
substances do not exceed the permissible exposure each of the following elements and shall indicate
limits specified in 29 CFR part 1910, subpart Z. specific measures that the employer will take to
ensure laboratory employee protection:
(d) Employee exposure determination
(i) Standard operating procedures relevant
(1) Initial monitoring. The employer shall mea- to safety and health considerations to be fol-
sure the employee’s exposure to any substance lowed when laboratory work involves the use
regulated by a standard which requires monitor- of hazardous chemicals;
ing if there is reason to believe that exposure levels
for that substance routinely exceed the action level (ii) Criteria that the employer will use to
(or in the absence of an action level, the PEL). determine and implement control measures
to reduce employee exposure to hazardous
(2) Periodic monitoring. If the initial monitor- chemicals including engineering controls,
ing prescribed by paragraph (d)(1) of this section the use of personal protective equipment and
discloses employee exposure over the action level hygiene practices; particular attention shall
(or in the absence of an action level, the PEL), be given to the selection of control measures
the employer shall immediately comply with the for chemicals that are known to be extremely
exposure monitoring provisions of the relevant hazardous;
standard.
(iii) A requirement that fume hoods and
(3) Termination of monitoring. Monitoring may other protective equipment are functioning
be terminated in accordance with the relevant properly and specific measures that shall be
standard. taken to ensure proper and adequate perfor-
mance of such equipment;
(4) Employee notification of monitoring results.
The employer shall, within 15 working days after (iv) Provisions for employee information
the receipt of any monitoring results, notify the and training as prescribed in paragraph (f) of
employee of these results in writing either indi- this section;
vidually or by posting results in an appropriate
location that is accessible to employees. (v) The circumstances under which a par-
ticular laboratory operation, procedure or
(e) Chemical hygiene plan—General. (Appendix A of activity shall require prior approval from the

OCR for page 289
293
APPENDIX A
employer or the employer’s designee before appendices which shall be made available to
implementation; employees;
(vi) Provisions for medical consultation and (ii) the location and availability of the em-
medical examinations in accordance with ployer’s Chemical Hygiene Plan;
paragraph (g) of this section;
(iii) T he permissible exposure limits for
(vii) Designation of personnel responsible OSHA regulated substances or recommended
for implementation of the Chemical Hygiene exposure limits for other hazardous chemicals
Plan including the assignment of a Chemical where there is no applicable OSHA standard;
Hygiene Officer, and, if appropriate, estab-
lishment of a Chemical Hygiene Committee; (iv) Signs and symptoms associated with
and exposures to hazardous chemicals used in the
laboratory; and
(viii) Provisions for additional employee pro-
tection for work with particularly hazardous (v) The location and availability of known
substances. These include “select carcino- reference material on the hazards, safe han-
gens,” reproductive toxins and substances dling, storage and disposal of hazardous
which have a high degree of acute toxicity. chemicals found in the laboratory including,
Specific consideration shall be given to the but not limited to, Material Safety Data Sheets
following provisions which shall be included received from the chemical supplier.
where appropriate:
(4) Training.
(A) Establishment of a designated area;
(i) Employee training shall include:
(B) Use of containment devices such as
fume hoods or glove boxes; (A) M ethods and observations that
may be used to detect the presence or
(C) Procedures for safe removal of con- release of a hazardous chemical (such as
taminated waste; and monitoring conducted by the employer,
continuous monitoring devices, visual
(D) Decontamination procedures. appearance or odor of hazardous chemi-
cals when being released, etc.);
(4) The employer shall review and evaluate the
effectiveness of the Chemical Hygiene Plan at least (B) The physical and health hazards of
annually and update it as necessary. chemicals in the work area; and
(f) Employee information and training. (g) Medical consultation and medical examinations.
(1) The employer shall provide employees with (1) The employer shall provide all employees
information and training to ensure that they are who work with hazardous chemicals an oppor-
apprised of the hazards of chemicals present in tunity to receive medical attention, including any
their work area. follow-up examinations which the examining
physician determines to be necessary, under the
(2) Such information shall be provided at the following circumstances:
time of an employee’s initial assignment to a work
area where hazardous chemicals are present and (i) Whenever an employee develops signs
prior to assignments involving new exposure situ- or symptoms associated with a hazardous
ations. The frequency of refresher information and chemical to which the employee may have
training shall be determined by the employer. been exposed in the laboratory, the employee
shall be provided an opportunity to receive
(3) Information. Employees shall be informed of: an appropriate medical examination.
(i) The contents of this standard and its (ii) Where exposure monitoring reveals an

OCR for page 289
294 PRUDENT PRACTICES IN THE LABORATORY
exposure level routinely above the action be revealed in the course of the examina-
level (or in the absence of an action level, the tion which may place the employee at
PEL) for an OSHA regulated substance for increased risk as a result of exposure to
which there are exposure monitoring and a hazardous workplace; and
medical surveillance requirements, medical
surveillance shall be established for the af- (D) A statement that the employee has
fected employee as prescribed by the particu- been informed by the physician of the
lar standard. results of the consultation or medical
examination and any medical condition
(iii) Whenever an event takes place in the that may require further examination or
work area such as a spill, leak, explosion or treatment.
other occurrence resulting in the likelihood of
a hazardous exposure, the affected employee (ii) The written opinion shall not reveal
shall be provided an opportunity for a medi- specific findings of diagnoses unrelated to
cal consultation. Such consultation shall be occupational exposure.
for the purpose of determining the need for a
medical examination. (h) Hazard identification.
(2) All medical examinations and consultations (1) With respect to labels and material safety data
shall be performed by or under the direct supervi- sheets:
sion of a licensed physician and shall be provided
without cost to the employee, without loss of pay (i) Employers shall ensure that labels on
and at a reasonable time and place. incoming containers of hazardous chemicals
are not removed or defaced.
(3) Information provided to the physician. The
employer shall provide the following information (ii) E mployers shall maintain any mate-
to the physician: rial safety data sheets that are received with
incoming shipments of hazardous chemicals,
(i) The identity of the hazardous chem - and ensure that they are readily accessible to
ical(s) to which the employee may have been laboratory employees.
exposed;
(2) T he following provisions shall apply to
(ii) A description of the conditions under chemical substances developed in the laboratory:
which the exposure occurred including quan-
titative exposure data, if available; and (i) If the composition of the chemical sub-
stance which is produced exclusively for
(iii) A description of the signs and symp- the laboratory’s use is known, the employer
toms of exposure that the employee is expe- shall determine if it is a hazardous chemical
riencing, if any. as defined in paragraph (b) of this section. If
the chemical is determined to be hazardous,
(4) Physician’s written opinion. the employer shall provide appropriate train-
ing as required under paragraph (f) of this
(i) F or examination or consultation re - section.
quired under this standard, the employer
shall obtain a written opinion from the ex- (ii) If the chemical produced is a byprod-
amining physician which shall include the uct whose composition is not known, the
following: employer shall assume that the substance is
hazardous and shall implement paragraph (e)
(A) Any recommendation for further of this section.
medical follow-up;
(iii) If the chemical substance is produced
(B) The results of the medical examina- for another user outside of the laboratory,
tion and any associated tests; the employer shall comply with the Hazard
Communication Standard (29 CFR 1910.120)
(C) Any medical condition which may

OCR for page 289
295
APPENDIX A
including the requirements for preparation of A. General Principles
material safety data sheets and labeling.
1. Minimize All Chemical Exposures
(i) Use of respirators. Where the use of respirators 2. Avoid Underestimation of Risk
is necessary to maintain exposure below permissible 3. Provide Adequate Ventilation
exposure limits, the employer shall provide, at no cost 4. Institute a Chemical Hygiene Program
to the employee, the proper respiratory equipment. 5. Observe the PELs and TLVs
Respirators shall be selected and used in accordance
with the requirements of 29 CFR 1910.134. B. Responsibilities
(j) Record-keeping. 1. Chief Executive Officer
2. Supervisor of Administrative Unit
(1) The employer shall establish and maintain 3. Chemical Hygiene Officer
for each employee an accurate record of any mea- 4. Laboratory Supervisor
surements taken to monitor employee exposures 5. Project Director
and any medical consultation and examinations 6. Laboratory Worker
including tests or written opinions required by
this standard. C. The Laboratory Facility
(2) The employer shall assure that such records 1. Design
are kept, transferred, and made available in ac- 2. Maintenance
cordance with 29 CFR 1910.20. 3. Usage
4. Ventilation
(k) Dates.
D. Components of the Chemical Hygiene Plan
(1) Effective date. This section shall become ef-
fective May 1, 1990. 1. Basic Rules and Procedures
2. C hemical Procurement, Distribution, and
(2) Start-up dates. Storage
3. Environmental Monitoring
(i) Employers shall have developed and 4. Housekeeping, Maintenance and Inspections
implemented a written Chemical Hygiene 5. Medical Program
Plan no later than January 31, 1991. 6. Personal Protective Apparel and Equipment
7. Records
(ii) Paragraph (a)(2) of this section shall not 8. Signs and Labels
take effect until the employer has developed 9. Spills and Accidents
and implemented a written Chemical Hy- 10. Training and Information
giene Plan. 11. Waste Disposal
(1) Appendices. The information contained in E. General Procedures for Working with Chemicals
the appendices is not intended, by itself, to create any
additional obligations not otherwise imposed or to 1. General Rules for All Laboratory Work with
detract from any existing obligation. Chemicals
2. Allergens and Embryotoxins
3. C hemicals of Moderate Chronic or High
Appendix A To 1910.1450—National Research Coun-
Acute Toxicity
cil Recommendations Concerning Chemical Hygiene
4. Chemicals of High Chronic Toxicity
In Laboratories (Non-Mandatory)
5. A nimal Work with Chemicals of High
Chronic Toxicity
Table Of Contents
Foreword F. Safety Recommendations
Corresponding Sections of the Standard and This G. Material Safety Data Sheets
Appendix

OCR for page 289
296 PRUDENT PRACTICES IN THE LABORATORY
Foreword Paragraph and topic in laboratory standard
appendix section Relevant
As guidance for each employer’s development (e)(3)(ii) Criteria to be used for implementation of D
of an appropriate laboratory Chemical Hygiene Plan, measures to reduce exposures.
the following non-mandatory recommendations are (e)(3)(iii) Fume hood performance. C4b
provided. They were extracted from “Prudent Practices
(e)(3)(iv) Employee information and training D10, D9
for Handling Hazardous Chemicals in Laboratories”
(including emergency procedures).
(referred to below as “Prudent Practices”), which was
(e)(3)(v) Requirements for prior approval of laboratory E2b, E4b
published in 1981 by the National Research Council
activities.
and is available from the National Academy Press,
(e)(3)(vi) Medical consultation and medical D5, E4f
2101 Constitution Ave., NW, Washington DC 20418.
examinations.
“Prudent Practices” is cited because of its wide distri-
bution and acceptance and because of its preparation (e)(3)(vii) Chemical hygiene responsibilities. B
by members of the laboratory community through the (e)(3)(viii) Special precautions for work with E2, E3, E4
sponsorship of the National Research Council. How- particularly hazardous substances.
ever, none of the recommendations given here will
modify any requirements of the laboratory standard.
In this appendix, those recommendations directed
This appendix merely presents pertinent recommen-
primarily at administrators and supervisors are given
dations from “Prudent Practices,” organized into a
in sections A-D. Those recommendations of primary
form convenient for quick reference during operation
concern to employees who are actually handling labo-
of a laboratory facility and during development and
ratory chemicals are given in section E. (References to
application of a Chemical Hygiene Plan. Users of this
page numbers in “Prudent Practices” are given in
appendix should consult “Prudent Practices” for a
parentheses.)
more extended presentation and justification for each
recommendation.
A. General Principles for Work with Laboratory
“Prudent Practices” deals with both safety and
Chemicals
chemical hazards while the laboratory standard is
concerned primarily with chemical hazards. There-
In addition to the more detailed recommenda-
fore, only those recommendations directed primarily
tions listed below in sections B-E, “Prudent Practices”
toward control of toxic exposures are cited in this ap-
expresses certain general principles, including the
pendix, with the term “chemical hygiene” being substi-
following:
tuted for the word “safety.” However, since conditions
producing or threatening physical injury often pose
1. It is prudent to minimize all chemical expo-
toxic risks as well, page references concerning major
sures. Because few laboratory chemicals are with-
categories of safety hazards in the laboratory are given
out hazards, general precautions for handling all
in section F. The recommendations from “Prudent Prac-
laboratory chemicals should be adopted, rather
tices” have been paraphrased, combined, or otherwise
than specific guidelines for particular chemicals
reorganized, and headings have been added. However,
(2,10). Skin contact with chemicals should be
their sense has not been changed.
avoided as a cardinal rule (198).
2. Avoid underestimation of risk. Even for sub-
Corresponding Sections of the Standard and This
stances of no known significant hazard, exposure
Appendix
should be minimized; for work with substances
which present special hazards, special precautions
The following table is given for the convenience of
should be taken (10, 37, 38). One should assume
those who are developing a Chemical Hygiene Plan
that any mixture will be more toxic than its most
which will satisfy the requirements of paragraph (e)
toxic component (30, 103) and that all substances
of the standard. It indicates those sections of this ap-
of unknown toxicity are toxic (3, 34).
pendix which are most pertinent to each of the sections
3. Provide adequate ventilation. The best way
of paragraph (e) and related paragraphs.
to prevent exposure to airborne substances is to
prevent their escape into the working atmosphere
Paragraph and topic in laboratory standard
by use of hoods and other ventilation devices (32,
appendix section Relevant
198).
(e)(3)(i) Standard operating procedures for handling C, D, E
4. I nstitute a chemical hygiene program. A
toxic chemicals.
mandatory chemical hygiene program designed

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APPENDIX A
to minimize exposures is needed; it should be a (e) Ensure that facilities and training for use
regular, continuing effort, not merely a standby of any material being ordered are adequate
or short-term activity (6,11). Its recommendations (215).
should be followed in academic teaching labora- 5. Project director or director of other specific
tories as well as by full-time laboratory workers operation, who has primary responsibility for
(13). chemical hygiene procedures for that operation
5. Observe the PELs, TLVs. The Permissible (7).
Exposure Limits of OSHA and the Threshold 6. Laboratory worker, who is responsible for:
Limit Values of the American Conference of Gov- (a) Planning and conducting each operation
ernmental Industrial Hygienists should not be in accordance with the institutional chemical
exceeded (13). hygiene procedures (7, 21, 22, 230); and
(b) D eveloping good personal chemical
hygiene habits (22).
B. Chemical Hygiene Responsibilities
Responsibility for chemical hygiene rests at all levels C. The Laboratory Facility
(6, 11, 21) including the:
1. Chief executive officer, who has ultimate 1. Design. The laboratory facility should have:
responsibility for chemical hygiene within the in- (a) A n appropriate general ventilation
stitution and must, with other administrators, pro- system (see C4 below) with air intakes and
vide continuing support for institutional chemical exhausts located so as to avoid intake of con-
hygiene (7, 11). taminated air (194);
2. Supervisor of the department or other ad- (b) Adequate, well-ventilated stockrooms/
ministrative unit, who is responsible for chemical storerooms (218, 219);
hygiene in that unit (7). (c) Laboratory hoods and sinks (12, 162);
3. Chemical hygiene officer(s), whose appoint- (d) Other safety equipment including eye-
ment is essential (7) and who must: wash fountains and drench showers (162,
(a) Work with administrators and other 169); and
employees to develop and (e) Arrangements for waste disposal (12,
(b) Monitor procurement, use, and disposal 240).
of chemicals used in the lab (8); 2. M aintenance. Chemical-hygiene-related
(c) See that appropriate audits are main- equipment (hoods, incinerator, etc.) should un-
tained (8); dergo continual appraisal and be modified if
(d) Help project directors develop precau- inadequate (11, 12).
tions and adequate facilities (10); 3. Usage. The work conducted (10) and its scale
(e) Know the current legal requirements (12) must be appropriate to the physical facilities
concerning regulated substances (50); and available and, especially, to the quality of ventila-
(f) Seek ways to improve the chemical hy- tion (13).
giene program (8, 11). 4. Ventilation—
4. Laboratory supervisor, who has overall re- (a) G eneral laboratory ventilation. This
sponsibility for chemical hygiene in the laboratory system should: Provide a source of air for
(21) including responsibility to: breathing and for input to local ventilation
(a) Ensure that workers know and follow devices (199); it should not be relied on for
the chemical hygiene rules, that protective protection from toxic substances released into
equipment is available and in working order, the laboratory (198); ensure that laboratory air
and that appropriate training has been pro- is continually replaced, preventing increase of
vided (21, 22); air concentrations of toxic substances during
(b) Provide regular, formal chemical hy - the working day (194); direct air flow into the
giene and housekeeping inspections includ- laboratory from non-laboratory areas and out
ing routine inspections of emergency equip- to the exterior of the building (194).
ment (21, 171); (b) Hoods. A laboratory hood with 2.5 lin-
(c) Know the current legal requirements ear feet of hood space per person should be
concerning regulated substances (50, 231); provided for every 2 workers if they spend
(d) Determine the required levels of protec- most of their time working with chemicals
tive apparel and equipment (156, 160, 162); (199); each hood should have a continuous
and monitoring device to allow convenient con-

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298 PRUDENT PRACTICES IN THE LABORATORY
firmation of adequate hood performance information on proper handling, storage, and
before use (200, 209). If this is not possible, disposal should be known to those who will be
work with substances of unknown toxicity involved (215, 216). No container should be ac-
should be avoided (13) or other types of local cepted without an adequate identifying label
ventilation devices should be provided (199). (216). Preferably, all substances should be received
See pp. 201-206 for a discussion of hood de- in a central location (216).
sign, construction, and evaluation. (b) Stockrooms/storerooms. Toxic substances
(c) Other local ventilation devices. Venti- should be segregated in a well-identified area
lated storage cabinets, canopy hoods, snor- with local exhaust ventilation (221). Chemicals
kels, etc. should be provided as needed (199). which are highly toxic (227) or other chemicals
Each canopy hood and snorkel should have a whose containers have been opened should be in
separate exhaust duct (207). unbreakable secondary containers (219). Stored
(d) Special ventilation areas. Exhaust air chemicals should be examined periodically (at
from glove boxes and isolation rooms should least annually) for replacement, deterioration,
be passed through scrubbers or other treat- and container integrity (218-19). Stockrooms/
ment before release into the regular exhaust storerooms should not be used as preparation or
system (208). Cold rooms and warm rooms repackaging areas, should be open during normal
should have provisions for rapid escape and working hours, and should be controlled by one
for escape in the event of electrical failure person (219).
(209). (c) Distribution. When chemicals are hand car-
(e) Modifications. Any alteration of the ven- ried, the container should be placed in an outside
tilation system should be made only if thor- container or bucket. Freight-only elevators should
ough testing indicates that worker protection be used if possible (223).
from airborne toxic substances will continue (d) L aboratory storage. Amounts permitted
to be adequate (12, 193, 204). should be as small as practical. Storage on bench
(f) P erformance. Rate: 4-12 room air tops and in hoods is inadvisable. Exposure to heat
changes/hour is normally adequate general or direct sunlight should be avoided. Periodic
ventilation if local exhaust systems such as inventories should be conducted, with unneeded
hoods are used as the primary method of items being discarded or returned to the store-
control (194). room/stockroom (225-6, 229).
(g) Quality. General air flow should not be
turbulent and should be relatively uniform 3. Environmental Monitoring
throughout the laboratory, with no high Regular instrumental monitoring of airborne concen-
velocity or static areas (194, 195); airflow trations is not usually justified or practical in laborato-
into and within the hood should not be ex- ries but may be appropriate when testing or redesign-
cessively turbulent (200); hood face velocity ing hoods or other ventilation devices (12) or when a
should be adequate (typically 60-100 lfm) highly toxic substance is stored or used regularly (e.g.,
(200, 204). 3 times/week) (13).
(h) E valuation. Quality and quantity of
ventilation should be evaluated on instal- 4. Housekeeping, Maintenance, and Inspections
lation (202), regularly monitored (at least (a) Cleaning. Floors should be cleaned regularly
every 3 months) (6, 12, 14, 195), and reevalu- (24).
ated whenever a change in local ventilation (b) Inspections. Formal housekeeping and chem-
devices is made (12, 195, 207). See pp. 195- ical hygiene inspections should be held at least
198 for methods of evaluation and for cal- quarterly (6, 21) for units which have frequent
culation of estimated airborne contaminant personnel changes and semiannually for others;
concentrations. informal inspections should be continual (21).
(c) Maintenance. Eye wash fountains should be
inspected at intervals of not less than 3 months (6).
D. Components of the Chemical Hygiene Plan
Respirators for routine use should be inspected
1. Basic Rules and Procedures (Recommendations periodically by the laboratory supervisor (169).
for these are given in section E, below.) Other safety equipment should be inspected
2. Chemical Procurement, Distribution, and Storage regularly (e.g., every 3-6 months) (6, 24, 171).
(a) Procurement. Before a substance is received,

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APPENDIX A
Procedures to prevent restarting of out-of-service (a) Emergency telephone numbers of emergency
equipment should be established (25). personnel/facilities, supervisors, and laboratory
(d) Passageways. Stairways and hallways should workers (28);
not be used as storage areas (24). Access to exits, (b) Identity labels, showing contents of contain-
emergency equipment, and utility controls should ers (including waste receptacles) and associated
never be blocked (24). hazards (27, 48);
(c) Location signs for safety showers, eyewash
5. Medical Program stations, other safety and first aid equipment, exits
(a) Compliance with regulations. Regular medi- (27) and areas where food and beverage consump-
cal surveillance should be established to the extent tion and storage are permitted (24); and
required by regulations (12). (d) Warnings at areas or equipment where special
(b) Routine surveillance. Anyone whose work or unusual hazards exist (27).
involves regular and frequent handling of toxi-
cologically significant quantities of a chemical 9. Spills and Accidents
should consult a qualified physician to determine (a) A written emergency plan should be estab-
on an individual basis whether a regular schedule lished and communicated to all personnel; it
of medical surveillance is desirable (11, 50). should include procedures for ventilation failure
(c) First aid. Personnel trained in first aid should (200), evacuation, medical care, reporting, and
be available during working hours and an emer- drills (172).
gency room with medical personnel should be (b) There should be an alarm system to alert
nearby (173). See pp. 176-178 for description of people in all parts of the facility including isola-
some emergency first aid procedures. tion areas such as cold rooms (172).
(c) A spill control policy should be developed
6. Protective Apparel and Equipment and should include consideration of prevention,
These should include for each laboratory: containment, cleanup, and reporting (175).
(a) Protective apparel compatible with the re- (d) All accidents or near accidents should be
quired degree of protection for substances being carefully analyzed with the results distributed to
handled (158-161); all who might benefit (8, 28).
(b) A n easily accessible drench-type safety
shower (162, 169); 10. Information and Training Program
(c) An eyewash fountain (162) (a) Aim: To assure that all individuals at risk are
(d) A fire extinguisher (162-164); adequately informed about the work in the labora-
(e) R espiratory protection (164-9), fire alarm tory, its risks, and what to do if an accident occurs
and telephone for emergency use (162) should be (5, 15).
available nearby; and (f) Other items designated (b) Emergency and Personal Protection Train-
by the laboratory supervisor (156, 160). ing: Every laboratory worker should know the
location and proper use of available protective
7. Records apparel and equipment (154, 169). Some of the
(a) Accident records should be written and re- full-time personnel of the laboratory should be
tained (174). trained in the proper use of emergency equipment
(b) Chemical Hygiene Plan records should docu- and procedures (6). Such training as well as first
ment that the facilities and precautions were com- aid instruction should be available to (154) and
patible with current knowledge and regulations encouraged for (176) everyone who might need it.
(7). (c) Receiving and stockroom/storeroom person-
(c) Inventory and usage records for high-risk nel should know about hazards, handling equip-
substances should be kept as specified in section ment, protective apparel, and relevant regulations
E3e below. (217).
(d) Medical records should be retained by the (d) Frequency of Training: The training and edu-
institution in accordance with the requirements cation program should be a regular, continuing
of state and federal regulations (12). activity-not simply an annual presentation (15).
(e) L iterature/Consultation: Literature and
8. Signs and Labels consulting advice concerning chemical hygiene
Prominent signs and labels of the following types should be readily available to laboratory person-
should be posted:

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300 PRUDENT PRACTICES IN THE LABORATORY
nel, who should be encouraged to use these infor- area with water (33, 172, 178) and remove any
mation resources (14). contaminated clothing (172, 178). If symptoms
persist after washing, seek medical attention
11. Waste Disposal Program (33). Clean-up. Promptly clean up spills, using
(a) Aim: To assure that minimal harm to people, appropriate protective apparel and equipment
other organisms, and the environment will result and proper disposal (24, 33). See pp. 233-237 for
from the disposal of waste laboratory chemicals specific clean-up recommendations.
(5). (b) Avoidance of ‘’routine” exposure: Develop
(b) Content (14, 232, 233, 240): The waste disposal and encourage safe habits (23); avoid unneces-
program should specify how waste is to be col- sary exposure to chemicals by any route (23). Do
lected, segregated, stored, and transported and not smell or taste chemicals (32). Vent apparatus
include consideration of what materials can be which may discharge toxic chemicals (vacuum
incinerated. Transport from the institution must pumps, distillation columns, etc.) into local ex-
be in accordance with DOT regulations (244). haust devices (199). Inspect gloves (157) and test
(c) Discarding Chemical Stocks: Unlabeled con- glove boxes (208) before use. Do not allow release
tainers of chemicals and solutions should undergo of toxic substances in cold rooms and warm
prompt disposal; if partially used, they should not rooms, since these have contained recirculated
be opened (24, 27). Before a worker’s employment atmospheres (209).
in the laboratory ends, chemicals for which that (c) Choice of chemicals: Use only those chemicals
person was responsible should be discarded or for which the quality of the available ventilation
returned to storage (226). system is appropriate (13).
(d) Frequency of Disposal: Waste should be re- (d) Eating, smoking, etc.: Avoid eating, drinking,
moved from laboratories to a central waste storage smoking, gum chewing, or application of cosmet-
area at least once per week and from the central ics in areas where laboratory chemicals are pres-
waste storage area at regular intervals (14). ent (22, 24, 32, 40); wash hands before conducting
(e) Method of Disposal: Incineration in an en- these activities (23, 24). Avoid storage, handling,
vironmentally acceptable manner is the most or consumption of food or beverages in storage
practical disposal method for combustible labora- areas, refrigerators, glassware or utensils which
tory waste (14, 238, 241). Indiscriminate disposal are also used for laboratory operations (23, 24,
by pouring waste chemicals down the drain 226).
(14,231,242) or adding them to mixed refuse for (e) Equipment and glassware: Handle and store
landfill burial is unacceptable (14). Hoods should laboratory glassware with care to avoid damage;
not be used as a means of disposal for volatile do not use damaged glassware (25). Use extra care
chemicals (40, 200). Disposal by recycling (233, with Dewar flasks and other evacuated glass ap-
243) or chemical decontamination (40, 230) should paratus; shield or wrap them to contain chemicals
be used when possible. and fragments should implosion occur (25). Use
equipment only for its designed purpose (23, 26).
(f) Exiting: Wash areas of exposed skin well be-
E. Basic Rules and Procedures for Working with
fore leaving the laboratory (23).
Chemicals
(g) Horseplay: Avoid practical jokes or other
The Chemical Hygiene Plan should require that labora- behavior which might confuse, startle or distract
tory workers know and follow its rules and procedures. another worker (23).
In addition to the procedures of the sub programs (h) Mouth suction: Do not use mouth suction for
mentioned above, these should include the rules listed pipeting or starting a siphon (23, 32).
below. (i) Personal apparel: Confine long hair and loose
clothing (23, 158). Wear shoes at all times in the
1. General Rules laboratory but do not wear sandals, perforated
The following should be used for essentially all labora- shoes, or sneakers (158).
tory work with chemicals: (j) Personal housekeeping: Keep the work area
(a) Accidents and Spills—Eye Contact: Promptly clean and uncluttered, with chemicals and equip-
flush eyes with water for a prolonged period (15 ment being properly labeled and stored; clean up
minutes) and seek medical attention (33, 172). the work area on completion of an operation or at
Ingestion: Encourage the victim to drink large the end of each day (24).
amounts of water (178). (k) Personal protection: Assure that appropriate
Skin Contact: Promptly flush the affected eye protection (154-156) is worn by all persons,

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APPENDIX A
including visitors, where chemicals are stored or ment plants, create fire or explosion hazards,
handled (22, 23, 33, 154). Wear appropriate gloves cause structural damage or obstruct flow (242).
when the potential for contact with toxic materi- (q) Working alone: Avoid working alone in a
als exists (157); inspect the gloves before each building; do not work alone in a laboratory if the
use, wash them before removal, and replace them procedures being conducted are hazardous (28).
periodically (157). (A table of resistance to chemi-
cals of common glove materials is given on p.159). 2. Working with Allergens and Embryotoxins
Use appropriate (164-168) respiratory equipment (a) Allergens (examples: diazomethane, isocya-
when air contaminant concentrations are not suf- nates, bichromates): Wear suitable gloves to pre-
ficiently restricted by engineering controls (164-5), vent hand contact with allergens or substances of
inspecting the respirator before use (169). Use unknown allergenic activity (35).
any other protective and emergency apparel and (b) Embryotoxins (34-5) (examples: organomer-
equipment as appropriate (22, 157-162). Avoid use curials, lead compounds, formamide): If you
of contact lenses in the laboratory unless neces- are a woman of childbearing age, handle these
sary; if they are used, inform supervisor so special substances only in a hood whose satisfactory per-
precautions can be taken (155). Remove laboratory formance has been confirmed, using appropriate
coats immediately on significant contamination protective apparel (especially gloves) to prevent
(161). skin contact. Review each use of these materials
(l) Planning: Seek information and advice about with the research supervisor and review con-
hazards (7), plan appropriate protective proce- tinuing uses annually or whenever a procedural
dures, and plan positioning of equipment before change is made. Store these substances, properly
beginning any new operation (22, 23). labeled, in an adequately ventilated area in an
(m) Unattended operations: Leave lights on, place unbreakable secondary container. Notify supervi-
an appropriate sign on the door, and provide for sors of all incidents of exposure or spills; consult
containment of toxic substances in the event of a qualified physician when appropriate.
failure of a utility service (such as cooling water)
to an unattended operation (27, 128). 3. Work with Chemicals of Moderate Chronic or
(n) Use of hood: Use the hood for operations High Acute Toxicity
which might result in release of toxic chemical Examples: diisopropylfluorophosphate (41), hydroflu-
vapors or dust (198-9). As a rule of thumb, use a oric acid (43), hydrogen cyanide (45). Supplemental
hood or other local ventilation device when work- rules to be followed in addition to those mentioned
ing with any appreciably volatile substance with above (Procedure B of “Prudent Practices”, pp. 39-41):
a TLV of less than 50 ppm (13). Confirm adequate (a) Aim: To minimize exposure to these toxic
hood performance before use; keep hood closed substances by any route using all reasonable pre-
at all times except when adjustments within the cautions (39).
hood are being made (200); keep materials stored (b) Applicability: These precautions are appro-
in hoods to a minimum and do not allow them to priate for substances with moderate chronic or
block vents or air flow (200). Leave the hood “on” high acute toxicity used in significant quantities
when it is not in active use if toxic substances are (39).
stored in it or if it is uncertain whether adequate (c) Location: Use and store these substances only
general laboratory ventilation will be maintained in areas of restricted access with special warning
when it is “off” (200). signs (40, 229). Always use a hood (previously
(o) Vigilance: Be alert to unsafe conditions and evaluated to confirm adequate performance with
see that they are corrected when detected (22). a face velocity of at least 60 linear feet per minute)
(p) Waste disposal: Assure that the plan for each (40) or other containment device for procedures
laboratory operation includes plans and training which may result in the generation of aerosols or
for waste disposal (230). Deposit chemical waste vapors containing the substance (39); trap released
in appropriately labeled receptacles and follow vapors to prevent their discharge with the hood
all other waste disposal procedures of the Chemi- exhaust (40).
cal Hygiene Plan (22, 24). Do not discharge to the (d) Personal protection: Always avoid skin con-
sewer concentrated acids or bases (231); highly tact by use of gloves and long sleeves (and other
toxic, malodorous, or lachrymatory substances protective apparel as appropriate) (39). Always
(231); or any substances which might interfere wash hands and arms immediately after working
with the biological activity of waste water treat- with these materials (40).
(e) Records: Maintain records of the amounts of

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302 PRUDENT PRACTICES IN THE LABORATORY
these materials on hand, amounts used, and the (e) Housekeeping: Use a wet mop or a vacuum
names of the workers involved (40, 229). cleaner equipped with a HEPA filter instead of dry
(f) Prevention of spills and accidents: Be pre- sweeping if the toxic substance was a dry powder
pared for accidents and spills (41). Assure that (50).
at least 2 people are present at all times if a (f) Medical surveillance: If using toxicologically
compound in use is highly toxic or of unknown significant quantities of such a substance on a
toxicity (39). Store breakable containers of these regular basis (e.g., 3 times per week), consult a
substances in chemically resistant trays; also work qualified physician concerning desirability of
and mount apparatus above such trays or cover regular medical surveillance (50).
work and storage surfaces with removable, ab- (g) R ecords: Keep accurate records of the
sorbent, plastic backed paper (40). If a major spill amounts of these substances stored (229) and
occurs outside the hood, evacuate the area; assure used, the dates of use, and names of users (48).
that cleanup personnel wear suitable protective (h) Signs and labels: Assure that the controlled
apparel and equipment (41). area is conspicuously marked with warning and
(g) Waste: Thoroughly decontaminate or in - restricted access signs (49) and that all containers
cinerate contaminated clothing or shoes (41). If of these substances are appropriately labeled with
possible, chemically decontaminate by chemical identity and warning labels (48).
conversion (40). Store contaminated waste in (i) Spills: Assure that contingency plans, equip-
closed, suitably labeled, impervious containers ment, and materials to minimize exposures of
(for liquids, in glass or plastic bottles half-filled people and property in case of accident are avail-
with vermiculite) (40). able (233-4).
(j) Storage: Store containers of these chemicals
4. Work with Chemicals of High Chronic Toxicity only in a ventilated, limited access (48, 227, 229)
Examples: dimethylmercury and nickel carbonyl (48), area in appropriately labeled, unbreakable, chemi-
benzo-a-pyrene (51), N-nitrosodiethylamine (54), other cally resistant, secondary containers (48, 229).
human carcinogens or substances with high carcino- (k) Glove boxes: For a negative pressure glove
genic potency in animals (38). Further supplemental box, ventilation rate must be at least 2 volume
rules to be followed, in addition to all those mentioned changes/ hour and pressure at least 0.5 inches
above, for work with substances of known high chronic of water (48). For a positive pressure glove box,
toxicity (in quantities above a few milligrams to a few thoroughly check for leaks before each use (49).
grams, depending on the substance) (47). (Procedure A In either case, trap the exit gases or filter them
of “Prudent Practices” pp. 47-50.) through a HEPA filter and then release them into
(a) Access: Conduct all transfers and work with the hood (49).
these substances in a “controlled area”: a restricted (l) Waste: Use chemical decontamination when-
access hood, glove box, or portion of a lab, desig- ever possible; ensure that containers of contami-
nated for use of highly toxic substances, for which nated waste (including washings from contami-
all people with access are aware of the substances nated flasks) are transferred from the controlled
being used and necessary precautions (48). area in a secondary container under the supervi-
(b) Approvals: Prepare a plan for use and dis- sion of authorized personnel (49, 50, 233).
posal of these materials and obtain the approval
of the laboratory supervisor (48). 5. Animal Work with Chemicals of High Chronic
(c) Non-contamination/Decontamination: Pro- Toxicity
tect vacuum pumps against contamination by (a) Access: For large scale studies, special facili-
scrubbers or HEPA filters and vent them into ties with restricted access are preferable (56).
the hood (49). Decontaminate vacuum pumps or (b) Administration of the toxic substance: When
other contaminated equipment, including glass- possible, administer the substance by injection or
ware, in the hood before removing them from the gavage instead of in the diet. If administration is in
controlled area (49, 50). Decontaminate the con- the diet, use a caging system under negative pres-
trolled area before normal work is resumed there sure or under laminar air flow directed toward
(50). HEPA filters (56).
(d) Exiting: On leaving a controlled area, remove (c) A erosol suppression: Devise procedures
any protective apparel (placing it in an appro- which minimize formation and dispersal of con-
priate, labeled container) and thoroughly wash taminated aerosols, including those from food,
hands, forearms, face, and neck (49). urine, and feces (e.g., use HEPA filtered vacuum